We report a case series of five anaemic patients (haemoglobin: 8.7 +/- 0.8 g.dl-1) with chronic obstructive lung disease in whom trials of weaning from the ventilator were unsuccessful. After transfer to our regional weaning centre, blood was transfused to increase the haemoglobin value to 12 g.dl-1 or higher. Subsequently, all patients were weaned successfully. We conclude from our experience that in anaemic patients with chronic obstructive lung disease there should not be a fixed transfusion threshold. In anaemic patients in whom difficulty in weaning from the ventilator is experienced, blood transfusion should be tailored to the individual patient's needs. Transfusion in those with chronic obstructive airways disease may lead to successful weaning.